Actually just checked up on this, and it came into force last September, and it isn't the fault of the PTE, but Northern Rail and the DfT - http://www.wymetro.com/peak-restrictions/
Also seems to affect tickets in Manchester too. However to be honest, the bus / metro network in Manchester kind of provides a half decent alternative (unless you are in Wigan at the start of the Evening Peak)
RE: What's annoying you today? V3
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Who needs heroes anyway? Villians have more fun.
Who needs heroes anyway? Villians have more fun.